linux-kernel - RE: [PATCH v22 2/4] scsi: ufs: L2P map management for HPB read

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Date:   Tue, 23 Feb 2021 07:50:39 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     "daejun7.park@...sung.com" <daejun7.park@...sung.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "bvanassche@....org" <bvanassche@....org>,
        "huobean@...il.com" <huobean@...il.com>,
        ALIM AKHTAR <alim.akhtar@...sung.com>,
        Javier Gonzalez <javier.gonz@...sung.com>
CC:     "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        JinHwan Park <jh.i.park@...sung.com>,
        SEUNGUK SHIN <seunguk.shin@...sung.com>,
        Sung-Jun Park <sungjun07.park@...sung.com>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        Jinyoung CHOI <j-young.choi@...sung.com>,
        BoRam Shin <boram.shin@...sung.com>
Subject: RE: [PATCH v22 2/4] scsi: ufs: L2P map management for HPB read

> +/*
> + * This function will parse recommended active subregion information in
> sense
> + * data field of response UPIU with SAM_STAT_GOOD state.
> + */
> +void ufshpb_rsp_upiu(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
> +{
> +       struct ufshpb_lu *hpb;
> +       struct scsi_device *sdev;
> +       struct utp_hpb_rsp *rsp_field = &lrbp->ucd_rsp_ptr->hr;
> +       int data_seg_len;
> +       bool found = false;
> +
> +       __shost_for_each_device(sdev, hba->host) {
> +               hpb = ufshpb_get_hpb_data(sdev);
> +
> +               if (!hpb)
> +                       continue;
> +
> +               if (rsp_field->lun == hpb->lun) {
> +                       found = true;
> +                       break;
This piece of code looks awkward, although it is probably working.
Why not just having a reference to the hpb luns, e.g. something like:
struct ufshpb_lu *hpb_luns[8] in struct ufs_hba.
Less elegant - but much more effective than iterating the scsi host on every completion interrupt.

> +               }
> +       }
> +
> +       if (!found)
> +               return;
> +
> +       if ((ufshpb_get_state(hpb) != HPB_PRESENT) &&
> +           (ufshpb_get_state(hpb) != HPB_SUSPEND)) {
> +               dev_notice(&hpb->sdev_ufs_lu->sdev_dev,
> +                          "%s: ufshpb state is not PRESENT/SUSPEND\n",
> +                          __func__);
> +               return;
> +       }
> +
> +       data_seg_len = be32_to_cpu(lrbp->ucd_rsp_ptr->header.dword_2)
> +               & MASK_RSP_UPIU_DATA_SEG_LEN;
> +
> +       /* To flush remained rsp_list, we queue the map_work task */
> +       if (!data_seg_len) {
data_seg_len should be 0x14

> +               if (!ufshpb_is_general_lun(hpb->lun))
> +                       return;
> +
> +               ufshpb_kick_map_work(hpb);
> +               return;
> +       }
> +
> +       /* Check HPB_UPDATE_ALERT */
> +       if (!(lrbp->ucd_rsp_ptr->header.dword_2 &
> +             UPIU_HEADER_DWORD(0, 2, 0, 0)))
> +               return;
> +
> +       BUILD_BUG_ON(sizeof(struct utp_hpb_rsp) != UTP_HPB_RSP_SIZE);
> +
> +       if (!ufshpb_is_hpb_rsp_valid(hba, lrbp, rsp_field))
> +               return;
How about moving both the data_seg_len and alert bit checks into ufshpb_is_hpb_rsp_valid,
And moving ufshpb_is_hpb_rsp_valid to the beginning of the function?
This way you would save redundant stuff if not a valid response. 

Thanks,
Avri